Battery modules having one or more lithium-ion battery cells can be found, for example, in motor vehicles, for instance electric motor vehicles or hybrid motor vehicles, in conjunction with drives of the motor vehicles.
Battery modules for use in the drive train of motor vehicles are also referred to as traction battery modules. Battery modules of this kind can be designed as systems comprising a battery cell and a battery management system. In order to provide the power which is required in hybrid vehicles and electric vehicles, battery cells are connected in series and in some cases also in parallel in the battery modules. In the case of electric vehicles, battery systems have, in some cases, voltages above 450 V, and in the case of hybrid vehicles even the voltage of 60 V, which is assumed as a safety threshold for contact with people, is exceeded. If battery systems of this kind are short-circuited due to external events, such as accidents or a malfunction in the actuation of a power switch, currents with current strengths which may cause the battery to burst or to catch fire may be produced in the battery cells.
FIG. 1 shows a basic circuit diagram of a traction battery module 5 according to the prior art, as is known from laid-open patent application DE 10 2009 000 682 for example. FIG. 1 shows two poles 10 and 20 which are electrically connected by means of a current path 30 on which battery cells 15, as voltage sources, are arranged in series, so that a voltage which is provided cumulatively by the cells 15 can be tapped off across the poles. In addition, the module has a charging and disconnecting device 40 at the positive pole 10, a disconnecting device 50 at the negative pole 20 and a service plug 60.
FIG. 2 shows a basic circuit diagram of a battery cell 15 according to the prior art, as is known from U.S. Pat. No. 5,939,217 for example. Said figure shows two poles 100 and 200 across which a voltage which is provided by the cell 15 can be tapped off from a voltage source 300. In addition, the cell has a fuse 400 at the positive pole 100. The fuse 400 has the function of reliably disconnecting the voltage source 300 from the positive pole 100 in the case of an abnormal state of temperature or current flow in the battery cell 15.
International patent application WO1993010589 discloses an apparatus for balancing out the states of charge of subunits of a battery. Each subunit is provided with a discharge circuit with resistors and fuses which are connected in series. The discharge circuit can be switched.